PPS NOTES with Video Lecture

PROGRAMMING FOR PROBLEM SOLVING

Unit 1 PDF
 Digital Computer  Output Unit
o Primary func ons of the output unit are to send the
 A digital computer is machine that stores data in a numerical
processed results to the user .
format and performs opera ons on that using mathema cal
o Output devices display informa on in a way that the
manipula ons .
user can understand .
o It converts these coded results to human acceptable .

 Processor
o Processor tells everything from your GPU to your disk
drivers and screen what to do.
o Example – intel , AMD
 Main Memory
o Main memory stores data and programs .
o Main memory is also known as Primary memory.
 I/O Modules
o It manages the communica on between a CPU and
network including transfer of data , management of
power , loads and control of machine func ons.
 System Bus
o It provides the communica on among processor ,
 CPU main memory , and I/O modules .
o It is a brain of computer .  Motherboard
o CPU is a primary component of a computer that acts as o Motherboard serves as a single pla orm to connect all
its control center . parts of a computer together .
 Memory unit o It connects CPU , memory , HDD etc.
o It can be referred as the storage area in which programs
are kept which are running that contains needed by
running programs .
o Memory unit generally categorize into two parts Memory hierarchy is organiza on of memory .It arranged according
o Primary memory Secondary memory to access me and capacity .
 Primary Memory
o Primary memory is the fast in execute the program.
o It is vola le in nature , because when computer is
shutdown , then all data stored in primary memory is
lost .
o Example – RAM ,ROM
 Secondary Memory
o Secondary memory is used when a large amount of data
and programs must be stored for a long-term basis.
o It is non-vola le in nature .
o Example – Magne c disks, pen drive , SSD
 ALU  Registers
o ALU operates the mathema cal calcula ons and logical o Register are special memory units which are used to
expressions. handle informa on between various units of computer
o Opera on such as mul plica on ,addi on, and speed up the rate of informa on transfer .
substruc on ,division , OR, AND , NOT etc.
 Cache
 Control Unit o It is smaller and faster memory that stores of couple of
o It is used to genera ng electric signals for various the data from frequently used main memory loca ons .
opera ons .
 Main memory
o It manages and controls all the opera ons of the
o It is also known as RAM .
computer .
o It is vola le and when power is lost , informa on is lost
 Input Unit too.
o Input unit are used by computer to read the data , most
 Secondary memory
used input services are keywords , mouse , joys cks etc.
o It is non-vola le and used to store large amount of data.
o It is also called auxiliary memory .
 Processor  Func ons of OS
o Memory management
 Processor is and integrated electronic circuit that perform o File management
calcula ons that run a computer. o Process management
 A processor performs arithme c, logical, I/O, and other basic o Device management
instruc ons.
Assembler
 Processor is also called CPU. But technically not correct since
 It converts assembly language to machine code and called a
CPU is just one processor inside a personal Computer.
translator . Assemblers are like compiler .
 GPU is another processor and even some hard drives technically
 It takes basic command and opera ons from assembly code
capable of performing some processing.
and converts them into binary code .
 Capabili es of processors are -: -
 It produces executable object code. It is a system s/w.
o Ability to process instruc ons at a given me
 Assembly language is a low-level language . and it is machine
o Max. number of instruc ons
dependent.
o Rela ve clock speed
 Opera ons performed by processors -: - Compiler
o Fetch retrieves instruc on from a RAM.  It translates a high-level language to machine language .
o Decode converts instruc on to signals.  High-level languages are JAVA, C , C++ , Python
o Execute decoded instruc on are send to each  Compiler scans all code of program and find errors and bugs ,
component so that desired opera ons can be and shows on the display , when no error and bugs find in file
performed. the compiler makes the object code of the program file .
 At compila on me , program will not terminate when any
RAM[Random Access Memory]
error in program .
 Ram is temporary memory bank, where your computer stores
 A er the compila on , when you run the object code file the , it
data it need to retrieve quickly .
will give the output .
 It is vola le memory.
Interpreter
ROM [Read Only Memory]
 Interpreter is a program which translates High level language to
 Rom is a non-vola le memory in nature.
machine code.
 When you have to store large amount of data , then you can use
 It runs the program line by line when any line through the error,
it .
then program will terminate .=
OS [opera ng System ]  It does not make the object code.
 OS is an interface between user and hardware.  It is slower than compiler.
 It operates all basic tasks like file managements memory
Linker
management , process management ,handle I/O modules .
 It is a program in a system which helps to link object modules of
 OS is a s/w that enables applica ons to interact with computer
a program into a single object file.
h/w .
 It performs process of linking . and also called link editors

 Linker is a program that links separately compiled modules into
one program.
 It also combines func ons in standard C library with code that
we wrote.
 Output of linker is an executable program . it is easy to
develop , test ,debug smaller program.
Loader
 Loader is program that loads machine codes of a program into
system memory.
 Executable file with extension exe is created , a er linking the
executable object code.
 Output of the loader is an object program .
 It is difficult to test and debug longer program.
Algorithm
 An algo. Is a set of instruc ons for solving a problems or tasks.
 Objec ves of OS
 It can be finite step by step procedure to achieve a required
o Convenience result.
OS makes computer more convenient to use .  Example -: - preparing a dish /Meal
o Efficiency Step of write an algorithm
OS allows the computer system resources to be used in  Obtain a descrip on of a problem.
an efficient manner.  Analyze the problem
o Ability to evolve  Develop high level algorithm
OS should be constructed in such a way as to permit  Refine algorithm by adding more details
effec ve development , tes ng .  Review the algo
 Proper es/characteris cs of Algorithm Step 1– Start the program.
 Input & output must be specified. Step 2– Read/input the number.
 Finiteness Step 3– Check if the number is even or odd.
 Definiteness Step 4– display the output.
 Effec veness Q. Flowchart and algo. To find a factorial of given number.
Flowchart
 It is a pictorial form of process.
 Every step indicated by shape. These shapes are connected by
lines/arrow to show the direc on of process.
Symbols of flowchart

step 1. Start
step 2. Read the number n
step 3. i=1, fact=1 step 4. Repeat
step 4 through 6 un l i=n
step 5. fact=fact*i
Advantages of Flowchart step 6. i=i+1
 Clearly shows how control structure operates. step 7. Print fact
 ‘START’ and ‘STOP ‘ symbols are clearly indicated. step 8. Stop
 Easy to understand Q. Flowchart and algo. To find greatest no. among three number.
Disadvantages of flowchart
 Logic complexity
 Difficult to show looping
 Time consuming
Pseudocode
 It is an informal language that helps programmers develop
algorithm .
 It is straigh orward and text-biased design tool.
 Example -: -
java code -> if (i<10){ i++; }
Pseudocode -> if i is less than 10 ,
Increment i by 1
Advantages of Pseudocode
 Easily modified
 Pseudocode easily converts into programming language.
Disadvantages of Pseudocode
 Not visual
 Communica on problem occurs due to lack of standardiza on.

Q. Flowchart and algo. to check given number is odd or even .

STEP
1:- START

STEP 2:- Declare three variables X,Y,Z.

STEP 3:-If X>Y&X>Z print X is the GREATEST.

STEP 4:-Otherwise if Y>Z&Y>X print Y is the GREATEST.

STEP 5:- Otherwise print Z is GREATEST.

STEP 6:- STOP

 Basic structure of C program Keywords
 Keywords are those words which specific meaning in C language.
#include<stdio.h> //preprocessor Directive
 Keywords should not be used as variable names to avoid
int sum(int,int); //function prototype of sum() problems or compile me errors.
 We have 32 keywords in C language ,which are these -: -
int a,b,c; //global variables
float d; //global variables

void main(){ //main function with return type

int x,y; //local variables
int z; //local variables
char ch ; //local variables
z=sum(x,y); //function call

int sum(int x1, int y1){ //function define sum()

return x1+y1; //return value of function sum

Standard I/O func on in C

 C language provides set of built-in input and outputs func ons
Execu on of C Program to read and write opera ons .
 Scanf func on reads the input from standard input stream or
 Crea ng the program
user input.
 Compiling the program
 Prin func on writes the output to standard output stdout and
 Linking program with func ons that are needed from the c
produces the output to the user.
library
 Execu ng the program
Components of C language
 Character set
Syntax Errors
o Ex ->Le ers, digits, special symbols , whitespaces
 syntax errors occur when a programmer does not follow the set
 Data type
of rules defined for the syntax of C language.
o Ex -> Int ,float , char ,double etc
 Syntax errors are some mes also called compila on errors .
 Constants
because they are always detected by the compiler.
o Ex> 2 , 4 ,5
 For example, if you leave off a closing brace ( } ) when defining a
 Variables
C func on, then trigger a syntax error.
o Ex-> Age , salary, name ,value
Logical Errors  Keywords
 A logic error is a 'bug' or mistake in a program's source code that o Ex ->For , do , if , con nue
results in incorrect or unexpected behaviour. Datatypes In C
 if our expecta on is one thing and result output is other thing
 C datatype are defined as the data storage format that a variable
then that kind of error we said it as “Logical errors”.
can store a data to perform a specific opera on.
 These error are called run me errors .
 Datatype is used to define a variable before to use in a program .
Object code  Integer Data Type can store zero, posi ve, and nega ve values
 Object code is the output of a compiler a er it processes the without any decimal.it is 4bytes.
source code.  char datatype to store characters and le ers. However, the char
 The object code is usually a machine code, also called a machine type is integer type because underneath C stores integer
language. numbers instead of characters.it is 1 byte.
 Object code generally refers to the output of a compiled file.  float data type is used to store floa ng-point values. Float in C
Executable code is used to store decimal and exponen al values.it is 8 bytes.
 Executable code is the output of a linker a er it processes the  long data type is also used to store big integer values. it is 8
object code. bytes.
 Executable code is also called executable file or executable  void type is usually used to specify the type of func ons returns
program. nothing .
ASCII Values  Double is more precise than float and can store 64 bits, double
 It stands for American Standard Code for Informa on of the number of bits float can store.it is 8 bytes.
Interchange. Variables in C
 ASCII value is used to represent the character variables in  A variable is a container . which store the data such as
numbers. integer,float,character,string etc.
 ASCII value of "a" is 97 and “z” is 122 and “A” is 65 “Z” is 90 and  Name of variable can be composed of le ers,digits and
“0” is 48 and “9” is 57 . underscore character.
 It must begin with either le er or an underscore .
 Upper and lower case le ers are dis nct.it means c language is
case sensi ve.
 Scope of variable
 It has three type 1. Local 2. Global 3. Sta c void main()
 Local variable is local to block in which variable is defined. {
 Global variable is global , i.e. if variable declared outside of the int i;
local func on , then variable is available to all func on that want for (i = 0; i < 3; i++)
to use it. {
 Sta c Variable is local to block in which the variable is define ,it
sum();
remains allocated in the memory throughout the life of the
}
program irrespec ve of whatever func on.
}
Storage classes in C
 C Storage Classes are used to describe the features of a
Output:
variable/func on. These features basically include the scope,
visibility, and life me. 10 24
 There are 4 types of storage classes . 11 25
 1.Automa c(auto) 2. External(extern) 12 26
 3. Sta c(sta c) 4. Register(register)
Example of register storage class

#include <stdio.h>
int main()
{
register int a;
printf("%d",a);
}

Output:
garbage
Example of external storage class

#include <stdio.h>
Example of Automa c storage class int a;
#include <stdio.h> int main()
int main() {
{ extern int a;
int a , i;
printf("%d", a);
printf("%d ", a);
}
int a = 20; Output: 0
for (i = 0; i < 3; i++)
{
printf("%d ", a);
}

a=5;
printf("%d ", a);
}
Output:
Garbage 20 20 20 5

Example of sta c storage class

#include <stdio.h>
void sum()
{
static int a = 10;
static int b = 24;
printf("%d %d \n", a, b);
a++;
b++;
}